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Make a retro scientific calculator with LED display and mechanical keypad.
04-11-2023, 11:05 AM
Post: #1
Make a retro scientific calculator with LED display and mechanical keypad.
Hi Guys, for several years, I am seeking a scientific calculator with a big screen and keyboard and never found one, so I decide to make a retro one. the simple way is using a calculator ASIC and connecting it to LEDs and a mechanical keypad. Unfortunately, there are too few chips with LED output directly, so I should make a LCD to LED converter first. After doing the first test, it runs OK. It's not an emulator but a "real" machine. Here is the prototype of the calculator with the original PCB. The next step is to integrate all the parts into a whole PCB, and add mechanical keys, wish you like it.

and here is a short video:


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04-14-2023, 06:02 PM
Post: #2
RE: Make a retro scientific calculator with LED display and mechanical keypad.
That's pretty nice. Maybe add a macropad for the keys. Will it be RPN?
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05-04-2023, 03:11 PM (This post was last modified: 05-09-2023 02:00 AM by geekvan.)
Post: #3
RE: Make a retro scientific calculator with LED display and mechanical keypad.
the 1st integrated pcb worked finally.

https://flic.kr/p/2oxYuAn
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05-05-2023, 02:49 AM
Post: #4
RE: Make a retro scientific calculator with LED display and mechanical keypad.
(05-04-2023 03:11 PM)geekvan Wrote:  the 1st integrated pcb worked finally.

[Image: 2oxYuAn]

If you ever sell a kit, I'm in!

Tom L
Cui bono?
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05-08-2023, 09:13 AM
Post: #5
RE: Make a retro scientific calculator with LED display and mechanical keypad.
(05-05-2023 02:49 AM)toml_12953 Wrote:  
(05-04-2023 03:11 PM)geekvan Wrote:  the 1st integrated pcb worked finally.

[Image: 2oxYuAn]

If you ever sell a kit, I'm in!

Thanks, but I'll make this project open and won't sell it.
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05-13-2023, 10:46 AM (This post was last modified: 05-13-2023 10:51 AM by geekvan.)
Post: #6
RE: Make a retro scientific calculator with LED display and mechanical keypad.
here is the final prototype without enclosure.

[Image: IMG-8854.jpg]

[Image: IMG-8855.jpg]

[Image: IMG-8856.jpg]

[Image: IMG-8857.jpg]

https://www.youtube.com/shorts/Iv_z6_ydeSI

all the sources can be found here:
https://github.com/geekvan007/retro_sharp506
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05-13-2023, 01:53 PM
Post: #7
RE: Make a retro scientific calculator with LED display and mechanical keypad.
Very nice indeed! Does the calculator chip have to come from a salvaged calculator?
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05-13-2023, 02:36 PM
Post: #8
RE: Make a retro scientific calculator with LED display and mechanical keypad.
(05-13-2023 01:53 PM)EdS2 Wrote:  Very nice indeed! Does the calculator chip have to come from a salvaged calculator?

Yes, The chip named SHARP-LI3301A from last century.
Thanks!
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05-13-2023, 03:03 PM (This post was last modified: 05-13-2023 03:18 PM by EdS2.)
Post: #9
RE: Make a retro scientific calculator with LED display and mechanical keypad.
Aha - looks like quite a few manufacturers used that chip (Edit: but these are programmable, which is confusing me):
Quote:Used in: ASTOR: 2, ATABA: AT687, AURORA: TB607, CANON: F300, CITIES: 8700, CITIZEN: SRP145, CITIZEN: SRP40, DYNA-TONE: G3/8700, IBICO: 098, INTERTRONIC: SC88P, KNIGHT: K31A, MBO: 610PR (version-1), MBO: 820PR, PIRACOMP: PR40, PIRACOMP: PR80, PRIVILEG: LC650PR, RADIO SHACK: EC4021, RADIO SHACK: EC4036, WHIRLPOOL: CW201
Also apparently Levis and Shangji.

Edit: is it the 42-key SHARP EL-506P we need? I see there was a 506A and 506H too, with different number of keys.

If so, there's a list of 20 clones here.

Edit: this is confusing!
Quote:With the replicas of the chip used in EL-506P, the first „clones” was built in similar housing as used in EL-506H, at various factories in Hong Kong, Taiwan and China. Later, with similar appearance and same model number, a simple programmable calculators based on a genuine Sharp chip — which was made for Sanyo — completed.
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05-13-2023, 03:56 PM
Post: #10
RE: Make a retro scientific calculator with LED display and mechanical keypad.
(05-13-2023 03:03 PM)EdS2 Wrote:  Aha - looks like quite a few manufacturers used that chip (Edit: but these are programmable, which is confusing me):
Quote:Used in: ASTOR: 2, ATABA: AT687, AURORA: TB607, CANON: F300, CITIES: 8700, CITIZEN: SRP145, CITIZEN: SRP40, DYNA-TONE: G3/8700, IBICO: 098, INTERTRONIC: SC88P, KNIGHT: K31A, MBO: 610PR (version-1), MBO: 820PR, PIRACOMP: PR40, PIRACOMP: PR80, PRIVILEG: LC650PR, RADIO SHACK: EC4021, RADIO SHACK: EC4036, WHIRLPOOL: CW201
Also apparently Levis and Shangji.

Edit: is it the 42-key SHARP EL-506P we need? I see there was a 506A and 506H too, with different number of keys.

If so, there's a list of 20 clones here.

Edit: this is confusing!
Quote:With the replicas of the chip used in EL-506P, the first „clones” was built in similar housing as used in EL-506H, at various factories in Hong Kong, Taiwan and China. Later, with similar appearance and same model number, a simple programmable calculators based on a genuine Sharp chip — which was made for Sanyo — completed.

It seems that the chip LI3301A is used for OEM manufacturers only. All SHARP calculators that use this chip are clones (fake). I bought many used calculators with this chip that have different suffixes, including 506P/506H/514.

Also, I heard that this chip has a clone one which was made by a Vietnam company.
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05-13-2023, 09:35 PM
Post: #11
RE: Make a retro scientific calculator with LED display and mechanical keypad.
I sure like those keys.

http://WilsonMinesCo.com (Lots of HP-41 links at the bottom of the links page, http://wilsonminesco.com/links.html )
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05-13-2023, 11:34 PM
Post: #12
RE: Make a retro scientific calculator with LED display and mechanical keypad.
Looks great and thanks for sharing your project.

But one feature is distracting and it is the blue LED MEM indicator.
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06-18-2023, 04:35 AM
Post: #13
RE: Make a retro scientific calculator with LED display and mechanical keypad.
Geekvan,
Who's the source of your keytops? And standard Cherry keyswitches?

Bill
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06-19-2023, 02:53 PM
Post: #14
RE: Make a retro scientific calculator with LED display and mechanical keypad.
(06-18-2023 04:35 AM)bwiese Wrote:  Geekvan,
Who's the source of your keytops? And standard Cherry keyswitches?

Bill

Hi Bill,

keytops were bought from China Taobao: blank xda and printed xda number keys.

https://item.taobao.com/item.htm?id=676692151586
https://item.taobao.com/item.htm?id=685502367565

and the key is compatible with Cherry MX.
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